Using Geophysics as a Tool for Groundwater Exploration
In recent years, our hydrogeologists have increasingly been using geophysics to support our groundwater exploration projects Western Canada
Waterline’s hydrogeologists are familiar with the applications and interpretation of a variety of geophysical methods for groundwater exploration in both Alberta and BC.
Waterline is familiar with the following geophysical techniques:
In-house downhole geophysical logging capabilities: A quick and effective way to confirm geology and assist with screen design and include methods such as gamma, resistivity (SPR or MPR), spontaneous potential, (SP), nuclear magnetic resonance (NMR), temperature, caliper, spinner, etc.
Ground geophysics: Used to map the subsurface in areas with limited borehole information and include methods such as seismic, transient electromagnetic method (TEM), electrical resistivity tomography (ERT), and electromagnetic (EM) surveys.
Waterline’s Approach to Geophysics
Waterline’s hydrogeologists commonly use the following approach when using geophysical techniques for groundwater exploration programs.
1. Clearly Defined Objectives
Involve the geophysicist early and work with them to come up with a plan that is specific to the site
Review the existing borehole and well data with the geophysicist
Spend a few extra hours during the planning stage – it will pay off down the road
2. Identified Limitations
Each method has its limitations
Consider interference with power lines, generators, underground infrastructure, haul trucks
Depth of the investigation
Different seismic sources have different depth limitations
A highly conductive clay unit can mask what is below (e.g., buried sand and gravel aquifer)
3. Set Realistic Expectations
Resolution will decrease with depth. Identifying thin aquifer units may not be possible
Complex 3D geology may not be well represented by a 2D survey line – may need multiple lines
Use geophysics as a tool along with drillers local knowledge and sound hydrogeologic principles
Drilling (ground truthing) will be needed to confirm the geophysical results
Regular communication between the geophysicist, hydrogeologist, and driller is key
Follow up and ask questions. Do the drilling results make sense with the geophysics? If not, what is the geophysics telling you?